Moved to New Zealand in 1952 when his father purchased a sheep farm.
Left school at 15 to enroll in a three-year dairy-farming course.
Changed his name from Smith to O'Brien (his maternal grandmother's maiden name) because there was already an established actor named Richard Smith.
Appeared in London stage productions of Hair and Jesus Christ Superstar in the early 1970s.
Got his start in films as a stuntman.
Wife Kimi Wong and he recorded pop singles in the mid-1970s under the name Kimi & Ritz.
Hosted the popular British game show The Crystal Maze from 1990 to 1993. His replacement, Ed Tudor-Pole, had also once played Riff Raff, the character O'Brien had originated in The Rocky Horror Picture Show.
In 2004, his contributions to the arts were honored with the erection of a statue of Riff Raff at a theater in Hamilton, New Zealand.
Was refused New Zealand citizenship in 2010 for being too old, but the country reconsidered and granted his request in 2011.
Provides the voice of Ferb's father in the animated kids TV series Phineas and Ferb.